1. Technical Field
The present invention relates to a conductive polymeric ink composition and, more particularly, to a conductive polymeric ink composition having superior coatability (processability) and conductivity.
2. Description of the Related Art
PEDOT:PSS (Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)) is actively utilized in photoelectronic organic devices and so on because of high electrical conductivity and transparency thereof. In particular, PEDOT:PSS films may be applied to touch screens, organic light emitting diodes, and e-papers. To this end, many attempts have been made to increase conductivity thereof using dimethyl sulfoxide, sorbitol, ionic liquids, and surfactants.
Meanwhile, a process of forming a uniform PEDOT:PSS film may be performed using various coating methods, for example, spin coating, bar coating, slot die coating, gravure printing, inkjet printing, spraying, off-set printing, etc. In order to apply such a composition to a printing process, a PEDOT:PSS ink composition has to possess coatability by the addition of an organic solvent. Although a PEDOT:PSS ink composition applicable to a printing process may be prepared by adding ink with a solvent having a high boiling point (bp: 100° C. or more), conductivity of the resulting coating film may decrease, which is undesirable. In particular, in an inkjet printing process, addition of a solvent having a high boiling point may increase jetting capability and spreadability of ink but may undesirably decrease conductivity.
Therefore, there is a need for an ink composition that satisfies both conductivity and coatability (processability).